1. Field of the Invention
This invention pertains generally to circuit interrupters and, more particularly, to circuit breakers including an alarm switch for activating an alarm to indicate that the circuit breaker has moved to a tripped position.
2. Background Information
Circuit interrupters, such as circuit breakers, are employed in diverse capacities in power distribution systems. A circuit breaker may include, for example, a line conductor, a load conductor, a fixed contact and a movable contact, with the movable contact being movable into and out of electrically conductive engagement with the fixed contact to switch the circuit breaker between an on or closed position and an off or open position, or between the on or closed position and a tripped position. The fixed contact is electrically conductively engaged with one of the line and load conductors, and the movable contact is electrically conductively engaged with the other of the line and load conductors.
Circuit breakers may also include an operating mechanism having a movable contact arm upon which the movable contact is disposed, a pair of links, a main spring, a latch mechanism, a cradle and a movable operating handle that extends outside of a housing for the circuit breaker. The cradle is pivotally disposed between the latch mechanism and the links. One portion of the cradle pivots with respect to the housing while another portion of the cradle has a latch ledge, which is latched by the latch mechanism. It is known to employ latch mechanisms including a primary latch and a secondary latch. See, for example, U.S. Pat. Nos. 6,747,534 and 6,140,897.
Inasmuch as the electrical disengagement of the movable contact from the fixed contact results in an interruption of current through the circuit breaker, it is known in the art to provide one or more switches that are mechanically operated by the operating mechanism and that are operatively connected with alarm bells, warning lights, and other devices that are calculated to inform a technician that the circuit breaker is in an interrupted or off condition. Such switches are components in a switch assembly that is mountable within the circuit breaker and often include an alarm switch that is operatively connected with the cradle or handle of the operating mechanism to detect a tripped state of the circuit breaker. In such applications, the switch usually includes an actuation lever in the form of a plastic part, a tang of spring steel or some other material that is connected at an attachment end thereof with the switch housing and that protrudes outwardly therefrom. A component of the operating mechanism, such as the cradle, includes one or more eccentric camming surfaces which, upon rotation of the component, moves, e.g., rotates, the actuation lever of the switch. Movement of the actuation lever by the camming surface causes the actuation lever to activate a micro-switch within the switch housing that actuates the electrical contacts within the switch that operate the alarm devices connected therewith. Circuit breakers employing an alarm switches in this manner are described in, for example, U.S. Pat. No. 6,633,210.
There is room for improvement in circuit breakers employing alarm switches.